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| author | Stephane Eranian <eranian@google.com> | 2012-02-09 23:20:56 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2012-03-05 14:55:41 +0100 |
| commit | 88c9a65e13f393fd60d8b9e9c659a34f9e39967d (patch) | |
| tree | a609acb6ae06c162015d6d32b9c8a1d5313ec3e2 | |
| parent | c5cc2cd906ea9fe73e3c93f9ad824996faa278cc (diff) | |
| download | blackbird-op-linux-88c9a65e13f393fd60d8b9e9c659a34f9e39967d.tar.gz blackbird-op-linux-88c9a65e13f393fd60d8b9e9c659a34f9e39967d.zip | |
perf/x86: Disable LBR support for older Intel Atom processors
The patch adds a restriction for Intel Atom LBR support. Only
steppings 10 (PineView) and more recent are supported. Older models
do not have a functional LBR. Their LBR does not freeze on PMU
interrupt which makes LBR unusable in the context of perf_events.
Signed-off-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1328826068-11713-7-git-send-email-eranian@google.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
| -rw-r--r-- | arch/x86/kernel/cpu/perf_event_intel_lbr.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/perf_event_intel_lbr.c b/arch/x86/kernel/cpu/perf_event_intel_lbr.c index e54a063b2863..07f0ff88e443 100644 --- a/arch/x86/kernel/cpu/perf_event_intel_lbr.c +++ b/arch/x86/kernel/cpu/perf_event_intel_lbr.c @@ -315,6 +315,16 @@ void intel_pmu_lbr_init_snb(void) /* atom */ void intel_pmu_lbr_init_atom(void) { + /* + * only models starting at stepping 10 seems + * to have an operational LBR which can freeze + * on PMU interrupt + */ + if (boot_cpu_data.x86_mask < 10) { + pr_cont("LBR disabled due to erratum"); + return; + } + x86_pmu.lbr_nr = 8; x86_pmu.lbr_tos = MSR_LBR_TOS; x86_pmu.lbr_from = MSR_LBR_CORE_FROM; |
